<!DOCTYPE html>
<html>
    <head>
        <title>更改元素</title>
    </head>
    <body>
        <p id = "demo">
            等待改变
        </p>

        <script src = "更改元素.js"></script>
        <button type = "button" onclick="myFunction()">点这里</button>
    </body>
</html>